A printed circuit board (PCB) is formed by printing a circuit line pattern on an electrical insulating substrate by using a conductive material such as copper (Cu), and refers to a board right before electronic parts are mounted thereon. In other words, the PCB refers to a circuit board in which the mounting positions of the electronic parts are determined, and a circuit pattern connecting the electronic parts is fixedly printed on a flat plate in order to densely mount electronic devices on the flat plate.
In the case of the PCB according to the related art, a circuit pattern is formed in a multi-layer configuration according to according to the design of a circuit. In this case, the circuit pattern may protrude upward from an insulating layer by etching a thin copper layer or plating the thin copper layer on the insulating layer.
Accordingly, the other insulating layer is formed on the insulating layer to cover the circuit pattern protruding from the insulating layer, and the other circuit pattern protrudes from the other insulating layer so that a total thickness of the PCB is increased and there is limitation to form a micro-circuit.
Meanwhile, in recent years, a buried pattern substrate having the reduced thickness and planarized surface has been used for the purpose of high performance and miniaturization of electronic parts.
FIG. 1 is a view showing a typical buried pattern PCB 10.
As shown in FIG. 1, the buried pattern PCB 10 includes a buried pattern groove 2 in the surface of an insulating substrate 1 and a circuit pattern 3 formed by filling the buried pattern groove 2 through a plating process.
The PCB 10 having the buried circuit pattern 3 can represent very strong adhesive strength with respect to an insulating member due to the structure of a base circuit pattern and a contact part, and the pitches of base circuit patterns and contact parts can be uniformly and finely formed.
However, when the buried circuit pattern 3 is formed through the plating scheme, plating variation occurs between a region having the pattern groove 2 and a region without the pattern groove 2, so that the etching process may not be uniformly performed after the plating process. Therefore, a predetermined region of the circuit pattern 3 may be not etched as shown in FIG. 1, so that the circuit pattern 3 may be shorted with respect to an adjacent circuit pattern. In addition, another region of the circuit pattern 3 may be over-etched, so that errors may occur in signal transmission.